Artificial legs



June 19, 1962 J. s. wAGGoTT ARTIFICIAL LEGS Filed Dec. 15, 1960 2 Sheets-Sheet 1 R 2 M 7g M 7 V 41||.|.||.l||| i/ f i? wwwlwmlwrm ill L. 1 1 f :IW/ T T T Xag X, f figli: u L LF 5\ 1/ I f f G I il l I l I llllll I|\| H l[ F EIIMMHMMHV Il w @IMT l@ l l I I l FP n Y fl TUHN B. WAGGOTT June 19, 1962 l J. B. wAGGoTT 3,039,116

' ARTIFICIAL LEGS Filed DSO. l5, 1960 2 SheetsSheet 2 INVENTCSR JOHN WAQGOTT 3,039,116 ARTIFICHAL LEGS John Berry Waggott, Alton, England, assigner to Vessa Limited, Alton, England Filed Dec. 15, 1960, Ser. No. 76,045 Claims priority, application Great Britain Dec. 16, 1959 3 Claims. (Cl. 3--22) This invention lconcerns improvements in artificial legs.

In artificial legs of the type shown in British Patent No. 762,695 a knee joint for artificial legs having an hydraulic damping device constructed so as to apply resistance to flexure only over a selected initial part of movement from the straight or standing position and to permit free movement through that part back to the straight position from a flexed position.

Experience with such improved `artificial legs has shown that `still better results and a more natural gait are made possible by applying a controlled resistance to movement in the joint over the last part of movement back to the straight position from a flexed position.

According to the present invention a knee joint for artificial legs of the type already mentioned is provided with means whereby the free movement of the two parts of the lim'b back to the straight position is halted a few degrees before that position is reached whereafter a controlled resistance to movement is `applied hydraulically.

In a preferred joint at least one orifice in a vane through which hydraulic iluid otherwise passes freely on a straightening movement is closed at a predetermined angular position of that vane whereafter further angular movement of the vane forces fluid through an orifice in a stationary block. This latter orifice is desirably fitted with a needle or like fine adjustment valve which controls resistance to iluid flow.

In one preferred constructional form of joint several orifices in the vane are simultaneously closed by springpressed balls which are housed in a block lfixed to the inner face of the hydraulic fluid chamber.

Alternative means for closing the orifice or orifices may be employed; for example, a stationary `cam may lbe used to close valves carried by the vane at an appropriate angular position, or non-return valves normally passing fluid freely on a straightening movement may be mechanically closed during the last few degrees of such movement.

The `above and other parts of the invention are embodied in a preferred constructional form of joint Which will now be described as an example with reference to the accompanying drawings in which:

FIG. 1 shows a plan View of the knee joint housing.

FIG. 2 shows a section of the knee joint perpendicular to the shaft through the line lI-II of FIG. 1 omitting a needle valve.

The artificial leg (not shown) has a thigh part and a shin part which are `connected and hinged iat a knee joint. This joint has a cylindrical fluid filled housing 1 which is anchored to the thigh part of the leg which forms part of the knee joint. The housing 1 has a cover pl-ate 2 at each end and these plates are spigotted and are held in position by screws 3. A shaft 4 passes through sealing rings 6 in the end of the housing 1 and -is carried in roller bearings 7 which are fitted in a recess in the housing end. This shaft 4 is locked at its ends to lugs (not shown) extending from the shin portion of the leg and thus constitutes the pivot pin for the knee joint. The shaft 4 carries a rotary vane 8 which is operable within the housing 1, and a web 9 extends from the inner wall of the housing 1 and fits closely to the shaft 4. Taken together, the vane 8 and the web 9 divide the interior of the housing 1 into two chambers 10, 11.

The wall of the web 9 has an aperture 13v to marry these two chambers, 10, 11, and a needle Valve 12 controls the rate of iiow through the aperture 13.

An arcuate plate 14 subtending a requisite tangle at the centre of the housing 1 is fixed within the housing 1 at a position to make close sliding contact with the outer edge of the vane 8 when the latter moves from the position it adopts in the straigh position A/A of the joint to a selected position B/ B under a degree of flexure.

A number of orifices 15 spaced over the width of the vane 8 are fitted with non-return clack valves 16 which permit free flow of fluid contained in the housing 1 through the vane 8 as it moves over the arcuate plate 14 towards the straight position A/A.

An equal number of spring-pressed balls 17 are housed in a block 18 which spans the length of the housing 1. One face of the block 18` is located at a position corresponding to that adopted by a face of the vane 8 in the straight position A/A and thus constitutes a stop.

The balls 17 protrude slightly from the said one face of the block 18, and, as the vane 8 approaches the block 18, they simultaneously close the orifices 15 in the vane 8 (which at this time are passing fluid freely through the non-return valves 16).

The balls 17 are free to move against the compression of their springs 19 for a short distance (representing the last few degrees of movement of the joint to the straight position A/A) whereafter the v-ane 8 contacts the block 18.

I claim:

1. In a knee joint, for artificial legs having upper and llower parts, of the type including a hydraulic housing xed to one part of the leg and a member reciprocally movable in said housing and operatively connected to the other part of the leg, said memfber having at least one opening therethrough and a check valve controlling said opening to permit free uid flow through said opening in one direction only so that said member is -freely movable in the direction opposite the direction of free fluid flow but movement in the other direction is resisted by fluid in the housing, and by-pass means enabling a limited flow of fluid between opposite sides of said member to permit said member to move in said other direction at a controlled rate, the improvement comprising means engageable between said member and said housing and operative to close said opening as said member approaches the end of its free movement stroke so that the final movement of said member in said stroke is controlled by the flu-id flow through said by-pass.

2. A knee joint for an artificial limb and including a vane fixed to one part of the limb and operating in a housing fixed to the other part of the limb and adapted to be lled with hydraulic fluid, said vane having at least one opening anda non return valve fitted with said opening and through which the hydraulic fluid passes freely on a straightening movement of the limb ibut is restricted on reverse movement of the limb, a stationary block fixed within the housing and having a by-pass orifice therein, and means to close said opening to stop the free liquid iiow therethrough at a predetermined angular position of the said vane on the straightening movement of the limb whereafter further angular movement of the vane forces fluid through said by-pass orifice.

3. A knee joint as in claim 2 in which said means comprises a spring-pressed ball which is housed in a block fixed to the inner face of the hydraulic fluid chamber.

References Cited in the file of this patent FOREIGN PATENTS 762,695 Great Britain Dec. 5,l 1956 

